Mike's reply #14 illustrates the effect of very large FoVs resulting from the gnomonic projection. (T'would have been even better with trees, buildings, cumulus clouds present.) The image scale varies continuously, with stretching in the radial direction becoming rapidly more severe at increasing distance from the center.
The gnomonic projection is a tangential one, and is the only type feasible for polygon based graphics intended to update at frame rates necessary for real-time simulators. This projection is the ONLY one which will render straight lines as perfectly straight anywhere in the display; all others render straight lines not passing through the center of projection as curved. The triangular polygons will thus always draw as straight of edge, making for the fastest rendering.
Incidentally, for the plotting of meteor paths by visual observers, charts of wide regions of the sky are available which use the gnomonic projection. If the start and end points of the meteors ionized trail are noted and plotted, drawing a straight line connecting them correctly represents the path on the sky, which is essentially a 'straight' line on the celestial sphere, or more correctly a great circle segment. During a meteor shower, these lines formed by shower members will point--as straight lines--back toward the shower radiant, or the apparent point of origin on the sky as Earth hurtles through the ancient stream of comet dust.
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Topic: FOV Modification for Triples or any widescreens (SOLVED) (Read 2018 times)
